Apparatus for continuous casting of metal



March 10, 1959 o. M. GARDNER I 2, 7

APPARATUS FOR commuous CASTING OF METAL Filed June 19, 1955 I nvvsN-rozzWg N .M- ARDNER AT T o RNEY vwater, or a gas, such as air. of thecasting below the mold, may be accomplished cedure commenced anew.

Unitfid States Paten 2,876,509 APPARATUS FOR CONTINUOUS CASTING OF METALOwen M. Gardner, Opportunity, Wash, assignor to Kaiser Aluminum &Chemical Corporation, Oakland, 'Cahf., a corporation of DelawareApplication June 19, 1953, Serial No. 362,853 7 Claims. (Cl. 22-572) Inthe art of continous casting of metals, the general I practice is toallow a vertical open-ended mold shell, to feed molten metalcontinuously into the top of the mold shell through suitable metaldelivery means such as astandpipe or pouring spout and continuouslywithdraw solid casting from the lower end of the mold; and to sup ply acooling fluid continuously to the mold and/or to the solid casting as itemerges from the mold. The metal may or may not be completely solidifiedin the mold; thus, the casting at the point where it emerges from themold may contain a core or crater of molten metal, which is solidifiedby cooling the casting below .the mold. The cooling fiuid may be aliquid, preferably Cooling of the mold, and

either by the use of a cooling jacket, such as a water jacket, or bydelivering coolant directly to the mold or casting, as by means of spraypipes or a perforated tank. Where ingots, billets and the like ofrelatively large cross-section are to be cast, a bafile or distributoris generally provided beneath the lower or exit end of the pouring spoutor standpipe for the purpose of causing the incoming molten metal to bedirected outwardly thereby reducing undesirable turbulence of the moltenmetal in the mold shell and reducing the tendency toward an excessivelydeep molten metal crater. The casting procedure may be a strictlycontinuous process (in which the casting is cut to length withoutinterruption of the casting procedure) or it may be semi-continuous; i.e., a casting of desired length may be cast, the flow of metal stopped,the casting removed and the pro Continuous casting as herein used refersto either type of operation.

It is recognized, in the continuous casting of metal, that it is highlydesirable that the rate of flow of molten metal into the mold be uniformor substantially uniform during the casting operation. Variations in therate of flow may lead to thermal cracks, shrinkage cracks, cold shuts,and other serious defects which render the casting unsuitable forsubsequent fabricating operations. Nonuniformity in rate of How ofmolten metal can be caused by various factors. For example, in any givencasting operation the level of the molten metal in the holding hearth ofthe furnace, or any other container for holding the body of moltenmetal, necessarily continues to fall thereby decreasing the pressure ofthe metal passing into the pouring spout or standpipe and thusdecreasing continuously the rate of flow of molten metal into the moldshell. The rate of flow can also be altered by other factors among whichmay be mentioned 'obstructions in the path of flow of the metal from themain the continuous casting ofmolten metal.

body of metal to the mold shell and changes in temperature of the metalwhich affects the viscosity thereof.

Various proposals have been made heretofore for ensuring proper controlof the rate of flow of molten metal, but for one or more reasons havenot been found to be commercially practicable. One such proposalinvolves the use of a plurality of pipe lines of relatively smallcross-section for supplying molten metal to the mold shell underpressure. The use of such plurality of pipes of small cross-sectiongives rise to the problem of clogging of the pipes. Moreover, suchapparatus is expensive in first cost and in maintenance. Anotherproposal has been to make use of intermediate containers or receptaclesfor molten metal between the casting station and the main furnace andwherein means are provided for maintaining a given level of metal in theintermediate container. Such apparatus makes the process of supplyingmolten metal complicated and costly.

According to the instant invention, uniformity of the rate of flow ofmolten metal into the mold is accomplished by means of a novel regulatorwhich is adapted to float on the body of molten metal within the moldshell. The regulator generally comprises a receptacle provided withsuitable float means and is adapted to float on the body ofmolten metalcontained in the mold beneath the metal delivery means, e. g. pouringspout or standpipe, through which the molten metal is fed to the mold.The receptacle of the regulator is adapted to co-act with the exit orlower end of the metal delivery means to automatically control the rateof flow of the molten metal from the delivery means such that the moltenmetal level in the mold shell is substantially constant at all times.The receptacle'is provided adjacent the bottom thereof with apertures togive a predetermined flow of metal outwardly into the body of Theregulator means of the instant invention is simple and relativelyinexpensive and yet is very efiicient in maintaining proper control ofthe rate of flow of molten metal into the mold shell. More- .over, thisapparatus is automatic in its operation or cofeed in the continuouscasting of metals wherein said regulator is simple, inexpensive andautomatic in its operation.

Another object of this invention is to provide a novel regulator formaintaining uniformity of molten metal feed in the casting of metalswhich compensates for factors affecting flow rate such as pressure,temperature, and obstructions to the path of metal flow.

Another object of this invention is to provide a novel regulator formaintaining uniformity in rate of molten metal feed into the mold ofcontinuous casting machines wherein the regulator additionally has meansprovided for controlling the path of flow of molten metal into the bodyof molten metal contained in the mold.

Other objects and advantages of the invention will be apparent from thefollowing description, taken in con junction with the drawings, andwherein:

Figure 1 is a plan view showing one form of continuous casting apparatusembodying the principle of the invention with parts removed for purposeof clarity, and

Figure 2 is a vertical, sectional view taken along line 22 of Figure 1.

Figure 3 is a fragmentary vertical, sectional view of the regulatorshown in Figure 2 and includes the provision of a screen for treatingmolten metal.

With further reference to the drawings which illustrate one preferredembodiment of the invention as applied to the casting of rectangular orsheet ingots of aluminum or aluminum alloys, at relatively shortopen-ended mold shell 1 is suitably mounted over a casting pit (notshown) by any of the conventional means. Within the mold shell 1 andextending therebelow is an embryo ingot 2 comprising a pool of moltenmetal 3 and solidified casting 4, the pool 3 extending downwardly andforming a molten metal crater or core within the ingot. The molten metalis continuously fed into the mold by the use of a suitable deliverymeans or pouring spout 5.

Positioned within the mold shell 1 and floating on the pool of moltenmetal is a regulator assembly 6. The regulator comprises a rectangularreceptacle or box-like mem her 7. On each side of receptacle 7 is afloat chamber 8 suitably secured to the receptacle. It will be seen thatthe float means provide sufficient buoyancy to the receptacle tomaintain the entire upper edge portion thereof above the surface of thebody or pool of molten metal 3. The float chambers are generallyair-containing and can either be made separately from the receptacle andthereafter joined thereto or can be made such that one wall of thechamber is formed by the side of the receptacle, as illustrated.Moreover, the float chambers can be made in-.

tegral with the receptacle. The receptacle and float chambers are madefrom a suitable material such as stainless steel. Mounted on the top ofthe float members at the ends of the receptacle 7 and extendingvertically therefrom is a rod 9. Suitably mounted across the top of moldshell 1 are a pair of elongated bar-like members 10 each having anaperture 11 therein. The rods 9 are slidably positioned within apertures11 in bars lltl. By this means the regulator assembly 6 is preventedfrom drifting or moving laterally with respect to mold shell 1 and spout5 while allowing vertical movement thereof relative to the pouring spout5. Alternatively, only one elongated cross member 19 may be used and insuch cases more than one rod 9 is mounted on a given float chamber.Although the float chambers as illustrated in Figures 1-3 are closed atthe top, it is to be understood that this is not necessary to thesatisfactory operation of the invention. It is preferable, however, touse closed chambers to prevent any tendency of foreign material gettinginto the chambers, e. g. molten metal, and altering the desiredoperating level of the regulator.

Secured to the inner surface of the bottom of receptacle '7 is athrottling member 12 which cooperates with the exit or lower end ofpouring spout S in controlling the rate of flow of molten metal enteringreceptacle 7. This member can be made of any suitable material such asnodular cast iron, silicon carbide or ceramic coated steel. Asillustrated in Figure 2, throttling member 12 projects upwardly from thebottom of receptacle 7 and the upper portion thereof is of conicalconfiguration. The lower or exit end of spout 5 is adapted, whennecessary, to closely seat on throttling member 12 when it comes incontact therewith thereby effectively interrupting the flow of moltenmetal into receptacle 7.

For purposes of allowing molten metal passing into receptacle 7 to flowout into molten metal pool or body 3, there is provided one or morehorizontal elongated slots 13 on either end of receptacle 7 adjacent thebottom thereof and wherein the slots are positioned below the bottom offloat chambers 8. in the application of casting sheet or rectangularingots as shown in Figures 1 and 2, it has been found desirable toprovide slots or other form of apertures only at the ends of thereceptacle. By this means, a relatively small regulator can be usedwhich will give the proper distribution of molten metal within the moldshell. In the casting of sheet or rectangular ingots, using a centralpouring spout, the edges and corners of the ingots are subjected toagreater rate of heat abstraction than in the case of the ingot facesand it is, therefore, desirable to direct the incoming flow of moltenmetal in the direction of the edges and corners in order to minimizeundesirable temperature differentials in the ingots.

In a continuous casting operation utilizing the regulator of the instantinvention, the regulator is first positioned slightly spaced from thetop of a conventional bottom block (not shown) of the casting apparatuswhich is within the mold shell in its uppermost position. In order toaccurately position the regulator relative to the bottom block prior tothe entry of molten metal, suitable means such as nuts 14 may beprovided in threaded engagei'hent with the upper portion of rods 9. Nuts14 are adapted to contact members 10 thereby limiting the downwardmovement of the regulator. These nuts also function to prevent theregulator from passing down and freezing in the ingot at the end of thecasting operation. The upper portion of each rod 9 is threaded for apredetermined distance to thereby allow adjustment of the regulator tovarious metal head levels. it Will be understood that means other thannuts ll4 can be provided for limiting the downward movement of theregulator as, for example, suitable arms mounted on the regulator whichare adapted to contact members 10 or the top of mold shell 1 at thedesired regulator position. The regulator is generally heated by anysuitable means prior to positioning within the mold shell to avoidpossible freezing of molten metal feed upon contact with the regulatorwith the undesirable results of clogging of the flow apertures or slotsand freezing of the regulator to the bottom block. After the heatedregulator has been positioned within the mold shell, bars 10 are placedover the mold shell such that rods 9 of the regulator pass throughapertures 11 in the bars. The ends of these bars are suitably secured tothe mold shell to thereby prevent lateral movement of the regulator whenin a floating position. immediately thereafter, molten metal is causedto pass down through spout 5, into receptacle 7 and out through slots orapertures 13 into the area defined by the mold shell and the top surfaceof the bottom block. When molten metal first passes into and out of thereceptacle the throttling member 12 will be spaced away from the lowerend of the spout 5 such that there is substantially no throttling of themetal tlow passing down the spout. After a predetermined amount ofmolten metal has passed into the mold shell, however, the regulater willbegin to float and move upwardly. At such time as the desired metal headis reached as determined by the co-action of the throttling member 12with the exit or lower end of spout 5, the bottom block is caused tomove downwardly thereby withdrawing solidified ingot from the moldshell. Should any variations in the metal flow occur during the castingoperation, regulator 6 will automatically compensate for same andmaintain the rate of molten metal flow into the mold shell substantiallyuniform. For example, in any given casting operation wherein the droprate of the bottom block and ingot is constant, should the pressure ofmolten metal passing down spout 5 be reduced and the rate of how benecessarily decreased, the metal head level will drop and the regulatorwill move downwardly thereby moving throttling member 12 away from theexit end of spout 5. This, in turn, will result in a greater flow ofmetal into the mold shell to compensate for the reduction in pressure.Conversely, should the pressure increase too great an amount, the metalhead level will increase and regulator 6 will be caused to move upwardlyand throttling member 12 will move closer to the exit end of spout 5 toreduce the volume or rate of flow of incoming metal to substantiallythat of the rate of withdrawal of solidified ingot from the mold shell.It will thus be seen that by use of the regulator of the instantinvention, variations in rate of flow of molten metal passing into themold shell are automatically and rapidly compensated for therebyensuring substantially uniform rate of metal flow at all times with theobvious attendant advantages resulting therefrom.

It is desirable casting practice to provide a screen in the metaltransfer trough leading from the furnace or other molten metal holdingmeans to the mold. Such positioning of the screen member in the moltenmetal transfer system, however, does not prevent impurities or foreignmatter in particulate form from getting into the molten metal streamsubsequent to passage through the screen member and becoming entrappedin the casting being produced. In the instant invention it has beenfound desirable to provide the screen member in the regulator as shownin Figure 3 such that all the molten metal feed will be screenedimmediately prior to passage into the metal head within the mold shell.As illustrated in Figure 3, screen member 15 is of dish-shapedcross-section with the edge of same projecting above the top of theregulator for ease of removal. A suitable opening 16 is provided in thebottom of the screen member such that throttling member 12 projectstherethrough. By this means the coaction between the throttling memberand the metal delivery means is not affected. Moreover, the screenmemher is maintained in proper position within the regulator. The screenmember can be made of any suitable material, e. g., black iron screenprovided with a refractory coating.

Although the embodiment of the invention described above in conjunctionwith Figures 1-3 of the drawings as applied to rectangular or sheetingots utilizes a float chamber on each side of the receptacle, it is tobe understood that a lesser number of chambers can be used as,

for example, two chambers, one on either end or short side of thereceptacle. The use of float chambers on each side of the receptacle ispreferably to ensure against undue rocking of the regulator when inoperative position and to give additional strength thereto againstwarpage. Additionally more than one pin or rod 9 on at least two sidesof the receptacle can be used to prevent any tendency toward rocking.The throttling member 12 may take various shapes other than that shownin Figures 2 and 3, as, for example, spherical, conical, frusto-conical,etc., the primary consideration being that the seating of the exit endof the spout 5 on the throttling member be such as to accurately controlthe rate of metal flow and to etfectively stop the flow of molten metalinto the receptacle and mold shell, if necessary, although in practiceit is generally found that increases in flow of molten metal are not sogreat as to necessitate completely stopping the metal flow. his to benoted that although the throttling member preferably is in the form of avertical projection as shown in Figures 2 and 3, it is contemplated,within the scope of the invention, that the bottom of the receptacle mayperform this function. In such case the shape of the exit end of spout 5would be made to conform to that portion of the receptacle bottom withwhich it would contact when the regulator was in its uppermost position.The bottom of receptacle 7 can be substantially flat, as shown in Figure7, or it can be of other configuration such as curved, etc.Additionally, the receptacle bottom can be suitably insulated forpurposes of preventing excessive heat transfer to the central portion ofthe molten crater and retention of heat in the upper portion of themetal head. Various means other than that disclosed for maintainingalignment of the regulator with respect to the molten metal deliverymeans can be used, as, for example,

suitable arms mounted on the mold shell engaging suitable guide meansprovided on the regulator.

It is also to be understood that although the embodiment of the instantinvention above described in conjunction with Figures 1-3 pertains toregulators for use in casting rectangular or sheet ingots, the inventionis equally applicable to the casting of circular, square or otherpolygonal shaped ingots, billets and the like. In such cases the floatmeans can be in the form of a continuous chamber around the periphery ofthe receptacle or, alternatively, can be in the form of separated spacedfloat chambers. In the casting of ingots, billets and the like ofvarious configurations by the instant invention the metal flow passagesprovided in the lower portion of the receptacle adjacent the bottomthereof may take the form of a plurality of apertures, so positioned anddesigned that the desired distribution of the incoming molten metalwithin the molten metal head is obtained.

Various changes, omissions and additions maybe made to this inventionwithout departing from the spirit and scope thereof as set forth in theappended claims.

What is claimed is:

1. In apparatus for the continuous casting of metal bodies, thecombination of an open mold shell adapted to contain a body of moltenmetal, downwardly directed delivery means for feeding molten metal intosaid mold shell, a regulator positioned beneath said delivery means andadapted to float on said body of molten metal, said regulator beingmovable relative to said delivery means, said regulator comprising areceptacle for receiving molten metal from said delivery means andwherein the lower end of said delivery means is adapted to extenddownwardly into the chamber defined by said receptacle, float meansaflixed to the side of said receptacle and adapted to contact the bodyof molten metal, said float means providing sufficient buoyancy to saidreceptacle to maintain the entire upper edge portion thereof above thesurface of the body of molten metal contained within said mold shell,said receptacle being provided with means for passage of molten metalfrom said receptacle to said body of molten metal below said float meansand below the surface of said body of molten metal, said regulator beingadapted to move vertically relative to vthe lower end of said deliverymeans upon change in the level of said body of molten metal to alter therate of flow of molten metal from said delivery means therebycompensating for such change in level of the body of molten metal.

2. In apparatus for the continuous casting of metal bodies, thecombination of an open mold shell adapted to contain a body of moltenmetal, downwardly directed delivery means for feeding molten metal intosaid mold shell, a regulator positioned beneath said delivery means endof said delivery means is adapted to extend downwardly into the chamberdefined by said receptacle, float means aflixed to the side of saidreceptacle and adapted to contact the body of molten metal, said floatmeans providing suflicient buoyancy to said receptacle to maintain theentire upper edge portion thereof above the surface of the body ofmolten metal contained within the mold shell, means for maintaining saidreceptacle in vertical alignment with said molten metal delivery means,said receptacle being provided with means for passage of molten metalfrom said receptacle to said body of molten metal and below the surface'of said molten metal body, and said receptacle being provided withthrottling means in alignment with the lower end of said delivery means,said regulator being adapted to move vertically relative to saiddelivery means upon change in the level of said body of molten metalwhereby said throttling means coacts with said lower end of the deliverymeans to alter the rate of flow of molten metal from said delivery meansthereby compensating for such change in level of the body of moltenmetal.

3. An apparatus according to claim 2 wherein said throttling means insaid receptacle comprises a vertically extending projection aflixed tothe bottom of said receptacle and wherein the lower end of said deliverymeans possesses a configuration which conforms to the configu- 7 rationof said throttling means such that contact of said delivery means withsaid throttling means is effective in stopping further flow of metalinto said mold shell.

4. In apparatus for the continuous casting of metal bodies, thecombination of an open mold shell adapted to contain a body of moltenmetal, downwardly directed delivery means for feeding molten metal intosaid mold shell, a regulator positioned beneath said delivery means andadapted to float on said body of molten metal, said regulator comprisinga receptacle for receiving molten metal from said delivery means andwherein the lower end of said delivery means is adapted to extend downwardly into the chamber defined by said receptacle, float means aflixedto the side of said receptacle and adapted to contact the body of moltenmetal, said float means providing sufiicient buoyancy to said receptacleto maintain the entire upper edge portion thereof above the surface ofthe body of molten metal contained within the mold shell, saidreceptacle being provided with means for passage of molten metal fromsaid receptacle to said body of molten metal below the surface of saidbody of molten metal, and means provided within said receptacle forscreening the molten metal feed passing into said body of molten metal,said regulator being adapted to move vertically relative to saiddelivery means upon change in the level of said body of molten metal toalter the rate of flow of molten metal from said delivery means therebycompensating for such change in level of the body of molten metal.

5. In, apparatus for the continuous casting of metal bodies, thecombination of an open mold shell adapted to contain a body of moltenmetal, downwardly directed delivery means for feeding molten metal intosaid mold shell, a regulator positioned beneath said delivery means andadapted to float on said body of molten metal, said regulator beingmovable relative to said delivery means, said regulator comprising areceptacle for receiving molten metal from said delivery means andwherein the lower end-of said delivery means is adapted to extenddownwardly into the chamber defined by said receptacle, float meansaffixed to said receptacle and adapted to contact the body of moltenmetal, said float means comprising at least one air-containing chamberaffixed to the side of said receptacle, said float means providingsufficient buoyancy to said receptacle to maintain the entire upper edgeportion thereof above the surface of the body of molten metal containedwithin the mold shell, said receptacle being provided with means forpassage of molten metal from said receptacle to said body of moltenmetal below said float means and below the surface of said molten metalbody, said regulator being adapted to move vertically relative to thelower end of said delivery means upon change in the level of said bodyof molten metal to alter the rate of flow of molten metal from saiddelivery means thereby compensating for such change in level of the bodyof molten metal.

6. In apparatus for the continuous casting of metal bodies, thecombination of an open mold shell having a substantially rectangularconfiguration adapted to contain a body of molten metal, downwardlydirected delivery means for feeding molten metal into said mold shell, aregulator positioned beneath said delivery means and adapted to float onsaid body of molten metal, said regulator being movable relative tosaid'delivery means, said regulator comprising a receptacle ofsubstantially rectangular configuration for receiving molten metal fromthe lower end of said delivery means and wherein the lower end of saiddelivery means is adapted to extend downwardly into the chamber definedby said receptacle, a float chamber affixed to each side of saidreceptacle and adapted to contact the body of molten metal, saidfioatmeans providing sufiicient buoyancy to said receptacle to maintainthe entire upper edge portion thereof above the surface of the body ofmolten metal contained thereby compensating within said mold shell,means for maintaining said receptacle in vertical alignment with saiddelivery means, said alignment means comprising a pair of spacedelongated bars passing across and aflixed to the upper end of said moldshell such that each bar overlies a float chamber afiixed to the shortsides of said receptacle, said bars each being provided with a verticalaperture therein, and a pair of vertically extending rods each of whichis aifixed at its lower end to the top of one of said float chambersaflixed to the short sides of said receptacle and wherein the upper endthereof is positioned in sliding relation within the aperture of thehorizontally positioned bar thereabove, said receptacle being providedwith means for passage of molten metal from said receptacle to said bodyof molten metal and below the surface thereof comprising a horizontallyextending elongated slot provided in the lower portion of each of theshort sides of said receptacle adjacent the bottom thereof, said slotsbeing below the bottom of said float chambers, throttling means providedwithin said receptacle in alignment with the lower end of said deliverymeans, said throttling means comprising a projection extendingvertically from the bottom of said receptacle, the upper portion of saidprojection being of conical configuration, said throttling means adaptedto move vertically relative to and co-act with the lower end of saiddelivery means upon change in the level of said body of molten metal toalter the rate of flow of molten metal from said delivery means for suchchange in level of the body of molten metal, means for limiting thedownward -movement of said regulator, and means provided within saidreceptacle for screening the metal feed passing into said molten metalbody from said receptacle, said throttling means projecting upwardlythrough said screening means.

7. In apparatus for the continuous casting of metal bodies, thecombination of an open mold shell adapted to contain a body of moltenmetal, downwardly directed delivery means for feeding molten metal intosaid mold shell, a regulator positioned beneath said delivery means andadapted to float on said body of molten metal, said reguiator beingmovable relative to said delivery means, said regulator comprising areceptacle for receiving molten metal from said delivery means andwherein the lower end of said delivery means is adapted to extenddownwardly into the chamber defined by said receptacle, float meansaffixed to the side of said receptacle and adapted to contact the bodyof molten metal, said float means providing sufficient buoyancy to saidreceptacle to maintain the entire 'upper edge portion thereof above thesurface of the body of molten metal contained within said mold shell,said receptacle being provided with means for passage of molten metalfrom said receptacle to said body of molten metal and below the surfaceof said molten metal body, said regulator being adapted to movevertically relative to the lower end of said delivery means upon changein the level of said body of molten metal to alter the rate of flow ofmolten metal from said .delivery means thereby compensating for suchchange in level of the body of molten metal.

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